Document 70E8y51zD75NYOX5KB6dw2eKe

Fume and Dust Exposure --from page 21 to control the exposure. Medical rec ord* of the indivtdaal* subjected to the exposure miy be ol value if the exclamations are thorough sad frequrot and no* of a cursory type. It must be remembered that occupa tional diseases are slow h developmcnt aad to some instances lasting ia effect. Sknr changes mar not be deteeted. and the mere fact that eases hare not occurred does not mean that exposures to known toxic materials mar be ignored. Driermtoatiea ol the ccccmtration of the toxic material in the air is is* portant |n evaluating the exposure. Tests of this type are indicative not oJy of the degree of contamination hut aim. in some instances, which operation is the major offender. The apparatus used m collecting the contaminant aad the method used in estimating the amount pmcot m the atmosphere vary with the type of material. Tests of this type are spec ialized in nature and are bod with many pitfall* which can lead to Wacom. ccmdmran* if done by inexperienced personnel. Percnlsslblo UmHi In a discussion pertaining to toxic materials it is generally necessary to quote permissible couceatrliens, or as it is sometimes njnriml miii mum allowable concentrations -per. mitsible Cahs. or threshold tmdt* Tbeae tenm are used ettfsmdj by industrial hygienists to * con. ceutxatioos of a substance la the air which are considered wifipftiMt tritb good health. The limit usually applies to exposures of eight hours duration for a prolonged period. The Emits are. for the moat part, advisory standards or beach marks which are practical to meet, la gmnil. these Emits are derived from three types of evidence all of which bare value nd linitittm* L Astasia tan bees expend at Jiumt momcrwuas and (he effoex* Mtad ' I A few expataesta b*t been ath beaaa (objects for Am periods of laa 1. Sate Hums base beta awtnd a by Awsrisr dw rswfiieinliui t mV etanes fa tba urinm tit cad aa telatiag tba Iwbewstfea vfcb nadts ef medical mmlnnhTm of sulas il The mere fact that these limits are exceeded does not necaoarily mean th^t tomeooe wiD become definitely IQ. But there b a good probability that someone wiD suffer ill effects if the I*TM* b greatly exceeded for a considmaldc period. There remains much to be learned regarding the toxkaty o! many substances used is inJurtry. So much for the general picture. Now let's look at some specific opera* tioaa. Wetdiof Welding processes most commonly used cart be divided into three types, arc. gas, and resistance. The safety wwaru pertaining to dothing. gog gle*, and helmets are of common knowledge and wiD not be considered here. Are welding when performed on uneoated dfd does not ptudoco a condition considered harmful to the welder, provided it u done fa) a com paratively large opa area. The famo which resah from welding consist es sentially of the oxides of Iren and oxides of metals which may comprise the steel or coating of the welding rod. Some investigators bare found characteristic msfirings on chest x-rays of men who have welded nnder severe conditions for long periods of time. Tboe markings are presumably doe to the deposition of cron fames within the hags, bat h bas not bea demonstrated that such fumes have cawed physical impairment. A frequently suggested Cart for welding fame b 15 mflligraan of iron oxide per cubic meter of arr. Con centrations of thb maxnitode existing in the workroom would materially re duce viability and thereby become a oebanee or an unsafe condition re qwring correction. Welding within confined areas such as tanka, inside tnsriiinriy or equipnot or m small rooms pimento a condition which can be of concern. The concentration of fame b materi ally higher under these condition* as there b tittle opportunity for dilution by natnrel air tuuwto normally prment in a large shop. Nitrogen oxides formed by the electric are when inhaled is anffirimt quantities causes finds to form in the lung iitma with rcaohant failure of the respira tory system. While welding in large open areas these toxic gases are nor mally not prestot in soffient quan tities to came harmful effects How ever, when welding b done in coofined areas, the ahrogoi oxides may reach a concentration which vriD be harmful. Cas welding generally is not productive of harmful fumes. Thoe arc, however, in brazing two potentially harmful exposure*. While boric riJ or lorates generally are used io here ing fluxes, some metals require flaxes containing significant quantities of fluoride compounds and fumes from these fhixes have been known to pro dues significant nasal irritation. Fluorides in general are looked upon with suspicion since they may pre dace harmful effects upon the bone structure. A Emit' of 2J5 mg. pa cubic meter has been suggested for fluorides, but no standard has beee. agreed upon. Most industrial hygien ists attempt to keep them as low n practicable. Silver solder is one of the more common alloys used is bearing. Sold ers of thb type vary in composition and may in some instances centals cadmium which, il volatilised in suf ficient quantities, u considered harm ful. At pnsot the,suggested limit far cadmium fume in air is 1 ---Pigrro per 10 cubic meters of air. Resistance, spot, or butt welding of plain steel is of no concern from the physiological standpoint The fames anting from such operations general ly are caused by the volatilized o8 which has come upon the metal stodi daring previous operations or has been placed open the metal as a not preventive. The preceding discussion of weld ing operations has been based opoa the assumption that the metob bring welded sue of plain steel. Tbe per formance of welding operations, ri cher arc, gas, or resistance, upon metals which have been coated with such toxic *"---irlf as lead, cadmw am, or mercury mxy cause harmfd exposures. Tbe beat of the flame or of tbe .arc causes volatilization of there metals. Welding or cutting of tone plate or othre metals eenlafamg significant quantities of lead can re salt la tbe vobtHbatian of lend fame, which if inhaled for a "Fmiw peri od of time, may result in lead aboorp- --To page ft Ifrfaasf Maly Dm friirey. ltN:; WITH MANAGEMENT BACKING* payroll savings plan can HELP BUSINESS AND NATION In 19,000 companic*, the Payroll Saving Plan (for the regular ourehareofU. 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